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<!--
O3D Picking Example.

This example shows one way to implement picking. Because O3D is shader
agnostic we can't handle picking automatically since we have no way of knowing
what the developer is going to do with their shaders. On the other hand, we can
provide various functions that make it possible to do your own picking. Only you
know which objects are pickable and which are not. For example if you are
making an RTS game, only you would know that units are pickable but ground and
explosions are not and that neither is your HUD.

It's possible that someone, maybe us, will create an engine to use o3d
that given a bunch of restrictions and flags on the data it excepts can
do picking in a more automatic way but that is not the goal of the o3d api.
Its goal is to provide a LOW-LEVEL shader agnostic API.
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
  "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>
O3D Picking Example.
</title>
<!-- Include default javascript library functions-->
<script type="text/javascript" src="../o3djs/base.js"></script>
<!-- Our javascript code -->
<script type="text/javascript" id="o3dscript">
o3djs.require('o3djs.util');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.pack');
o3djs.require('o3djs.camera');
o3djs.require('o3djs.picking');
o3djs.require('o3djs.scene');
o3djs.require('o3djs.debug');

// Events
// init() once the page has finished loading.
// unload() when the page is unloaded.
window.onload = init;
window.onunload = unload;

// constants
var NORMAL_SCALE_FACTOR = 2.0;

// global variables
var g_o3d;
var g_math;
var g_client;
var g_pack;
var g_viewInfo;
var g_treeInfo;  // information about the transform graph.
var g_pickInfoElem;
var g_debugHelper;
var g_debugLineGroup;
var g_debugLine;
var g_selectedInfo = null;
var g_flashTimer = 0;
var g_highlightMaterial;
var g_highlightShape;
var g_finished = false;  // for selenium testing.

function updateInfo() {
  if (!g_treeInfo) {
    g_treeInfo = o3djs.picking.createTransformInfo(g_client.root,
                                                        null);
  }
  g_treeInfo.update();
}

function unSelectAll() {
  if (g_selectedInfo) {
    // Remove it from the transform of the selected object.
    g_selectedInfo.shapeInfo.parent.transform.removeShape(g_highlightShape);
    // Remove everything related to it.
    o3djs.shape.deleteDuplicateShape(g_highlightShape, g_pack);
    g_highlightShape = null;
    g_selectedInfo = null;
  }
}

function select(pickInfo) {
  unSelectAll();
  if (pickInfo) {
    g_selectedInfo = pickInfo;
    // make a copy of the selected shape so we can use it to highlight.
    g_highlightShape = o3djs.shape.duplicateShape(
        g_pack,
        g_selectedInfo.shapeInfo.shape,
        'highlight_');
    // Set all of it's elements to use the highlight material.
    var elements = g_highlightShape.elements;
    for (var ee = 0; ee < elements.length; ee++) {
      elements[ee].material = g_highlightMaterial;
    }

    // Add it to the same transform
    g_selectedInfo.shapeInfo.parent.transform.addShape(g_highlightShape);
    g_flashTimer = 0.0;  // make it change color immediately.
  }
}

function pick(e) {
  var worldRay = o3djs.picking.clientPositionToWorldRay(
      e.x,
      e.y,
      g_viewInfo.drawContext,
      g_client.width,
      g_client.height);
  unSelectAll();

  // Update the entire tree in case anything moved.
  // NOTE: This function is very SLOW!
  // If you really want to use picking you should manually update only those
  // transforms and shapes that moved, were added, or deleted by writing your
  // own picking library. You should also make sure that you are only
  // considering things that are pickable. By that I mean if you have a scene of
  // a meadow with trees, grass, bushes, and animals and the only thing the user
  // can pick is the animals then put the animals on their own sub branch of the
  // transform graph and only pick against that subgraph.
  // Even better, make a separate transform graph with only cubes on it to
  // represent the animals and use that instead of the actual animals.
  g_treeInfo.update();

  var pickInfo = g_treeInfo.pick(worldRay);
  if (pickInfo) {
    select(pickInfo);
    g_pickInfoElem.innerHTML = pickInfo.shapeInfo.shape.name;

    // Display the normal
    // NOTE: Lookup the normal with this function is very SLOW!!
    // If you need performance, for a game or something, you should consider
    // other methods.
    var normal = o3djs.element.getNormalForTriangle(
        pickInfo.element,
        pickInfo.rayIntersectionInfo.primitiveIndex);

    // Convert the normal from local to world space.
    normal = g_math.matrix4.transformNormal(
        pickInfo.shapeInfo.parent.transform.worldMatrix,
        normal);

    // Remove the scale from the normal.
    normal = g_math.normalize(normal);

    // Get the world position of the collision.
    var worldPosition = pickInfo.worldIntersectionPosition;

    // Add the normal to it to get a point in space above it with some
    // multiplier to scale it.
    var normalSpot = g_math.addVector(
        worldPosition,
        g_math.mulVectorScalar(normal, NORMAL_SCALE_FACTOR));

    // Move our debug line to show the normal
    g_debugLine.setVisible(true);
    g_debugLine.setEndPoints(worldPosition, normalSpot);
  } else {
    g_debugLine.setVisible(false);
    g_pickInfoElem.innerHTML = '--nothing--';
  }
}

function onrender(renderEvent) {
  g_flashTimer += renderEvent.elapsedTime;
  g_flashTimer = g_flashTimer % 0.5;
  if (g_selectedInfo) {
    if (g_flashTimer < 0.25) {
      g_highlightMaterial.getParam('color').value = [1, 1, 1, 1];
    } else {
      g_highlightMaterial.getParam('color').value = [0, 0, 0, 1];
    }
  }
}

/**
 * Loads a scene into the transform graph.
 * @param {!o3d.Pack} pack Pack to load scene into.
 * @param {string} fileName filename of the scene.
 * @param {!o3d.Transform} parent parent node in the transform graph to
 *      which to load the scene into.
 */
function loadScene(pack, fileName, parent) {
  // Get our full path to the scene
  var scenePath = o3djs.util.getCurrentURI() + fileName;

  // Load the file given the full path, and call the callback function
  // when its done loading.
  o3djs.scene.loadScene(g_client, pack, parent, scenePath, callback);

  /**
   * Our callback is called once the scene has been loaded into memory
   * from the web or locally.
   * @param {!o3d.Pack} pack The pack that was passed in above.
   * @param {!o3d.Transform} parent The parent that was passed in above.
   * @param {*} exception null if loading succeeded.
   */
  function callback(pack, parent, exception) {
    if (exception) {
      alert('Could not load: ' + fileName + '\n' + exception);
      return;
    }
    // Get a cameraInfo (an object with a view and projection matrix)
    // using our javascript library function
    var cameraInfo = o3djs.camera.getViewAndProjectionFromCameras(
        parent,
        g_client.width,
        g_client.height);

    // Copy the one from the file to ours.
    g_viewInfo.drawContext.view = cameraInfo.view;
    g_viewInfo.drawContext.projection = cameraInfo.projection;

    // Generate draw elements and setup material draw lists.
    o3djs.pack.preparePack(pack, g_viewInfo);

    // Update our info
    updateInfo();

    g_treeInfo.dump('');

    g_finished = true;  // for selenium testing.
  }
}

/**
 * Creates the client area.
 */
function init() {
  o3djs.util.makeClients(initStep2);
}

/**
 * Initializes O3D and loads the scene into the transform graph.
 * @param {Array} clientElements Array of o3d object elements.
 */
function initStep2(clientElements) {
  // Initializes global variables and libraries.
  var o3dElement = clientElements[0];
  o3dElement.name = 'o3dObj';  // This is only for our selenium tests.
  g_o3d = o3dElement.o3d;
  g_math = o3djs.math;
  g_client = o3dElement.client;

  g_pickInfoElem = document.getElementById('pickInfo');

  // Creates a pack to manage our resources/assets
  g_pack = g_client.createPack();

  // Create the render graph for a view.
  g_viewInfo = o3djs.rendergraph.createBasicView(
      g_pack,
      g_client.root,
      g_client.renderGraphRoot);

  // Use the debug library to create a line we can position to show
  // the normal.
  g_debugHelper = o3djs.debug.createDebugHelper(g_client.createPack(),
                                                g_viewInfo);
  g_debugLineGroup = g_debugHelper.createDebugLineGroup(g_client.root);
  g_debugLine = g_debugLineGroup.addLine();
  g_debugLine.setColor([0,1,0,1]);

  // Create a material for highlighting.
  g_highlightMaterial = o3djs.material.createConstantMaterial(
      g_pack,
      g_viewInfo,
      [1, 1, 1, 1]);
  // Setup a state to bring the lines forward.
  var state = g_pack.createObject('State');
  state.getStateParam('PolygonOffset2').value = -1.0;
  state.getStateParam('FillMode').value = g_o3d.State.WIREFRAME;
  g_highlightMaterial.state = state;

  // Creates a transform to put our data on.
  var my_data_root = g_pack.createObject('Transform');

  // Connects our root to the client's root.
  my_data_root.parent = g_client.root;

  // Load the scene into the transform graph as a child of my_data_root
  loadScene(g_pack, 'assets/seven_shapes.o3dtgz', my_data_root);

  g_client.setRenderCallback(onrender);

  // Start picking; it won't do anything until the scene finishes loading.
  o3djs.event.addEventListener(o3dElement, 'mousedown', pick);
}

/**
 * Removes any callbacks so they don't get called after the page has unloaded.
 */
function unload() {
  if (g_client) {
    g_client.cleanup();
  }
}
</script>
</head>
<body>
<h1>Picking</h1>
Click on an object
<br/>
<!-- Start of O3D plugin -->
<div id="o3d" style="width: 600px; height: 600px;"></div>
<!-- End of O3D plugin -->
<div style="font-family: sans-serif; font-size: large;">PICKED: <span id="pickInfo"></span></div>
</body>
</html>
